>>Why would you sell something you could make profit on if you kept it for yourself?
Anyone building a bunch of good mining rigs could certainly have a decent amount of bitcoins - but lots of people don't want to hold a large amount of a currency that is risky, volatile, possibly illegal, difficult to exchange for their local currency (that their taxes and rent need to be paid in), impossible to pay their vendors in, etc.
If you want gold, mine gold. If you want dollars, sell shovels.
Anyone building a bunch of good mining rigs could certainly have a decent amount of bitcoins - but lots of people don't want to hold a large amount of a currency that is risky, volatile, possibly illegal, difficult to exchange for their local currency (that their taxes and rent need to be paid in), impossible to pay their vendors in, etc.
If you want gold, mine gold. If you want dollars, sell shovels.